Monday, 6 April 2015

Modified Difference Concept (Internal Transfer: Small to Big)

First
Cindy folded 226 fewer paper stars than Farah. When Cindy gave Farah 25 of her paper stars, the ratio of Cindy's paper stars to Farah's paper stars became 1 : 5.

a) How many stars did Cindy folded at first?
b) How many paper stars did Farah have in the end?


(After)
Farah = 5u
Cindy = 1u

New Difference = Old Difference + Double Change (Small to Big)
Difference = 4u
4u = 226 + 2 × 25 = 226 + 50 = 276

Farah = 5u = 276 ÷ 4 × 5 = 69 × 5 = 345

Cindy (Before) = 1u + 25 = 69 + 25 = 94

Second

A group of pupils took a test. The number of pupils who passed was 146 more than the number of pupils who failed. If 18 more pupils had passed the test, the number of pupils who passed will be 3 times the number of pupils who failed. Find the total number of pupils who took the test.

(After)
Passed : Failed
= 3 : 1

New Difference = Old Difference + Double Change
Difference = 3 -1 = 2 units
2 units = 146 + 2 × 18 = 182

Total = 4 units = 364

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